Cannot start POSTMASTER - Mailing list pgsql-ports

Dear Sir,

I just installed a Red-Had Linux 6.0 on my PC (Pentium 133). I have selected
the POSTGRESQL while installation.
When I used linuxconf to enable the POSTGRESQL, I got the error message
"Invalid PID file: /var/run/postmaster.pid"
When I run POSTMASTER on terminial, I got the following message :
    "/usr/bin/postmaster does not know where to find the database system
data.  You
    must specify the directory that contains the database system either
by specifying
     the -D invocation option or by setting the PGDATA environment
variable.  "

Please help me to solve this problem.

Regards,
Pak